The UK Daily Mail has these details, reported here:
There were reports that a fire engine pumping water in to the Number Two reactor failed shortly before last night's explosion -- which would have led to an increase in temperature inside the reactor and could have caused the blast. ...
The latest explosion last night is feared to have cracked the main protective barrier around reactor number two at the plant.
The International Atomic Agency said radioactive material is leaking 'directly' into the air from the stricken plant at a rate of 400 millisieverts per hour. Anyone exposed to over 100 millisieverts a year risks cancer.
Engineers are using sea water to cool overheating nuclear fuel rods.
That is a sign of the desperation of the situation because the corrosive salt water will put the reactors permanently out of action. It is the first time in 57 years that sea water has been used to cool a reactor.
Although the plant’s three working reactors shut down automatically when the magnitude nine earthquake struck on Friday, the cooling systems which keep the radioactive uranium and plutonium fuel rods cool have been hit by a series of failures. ...
'It is too dangerous to go outside and even if they did they would not be able to be transported to a safe place because we have no fuel for our vehicles,' [the mayor of Fukushima City] said.
